Question

基本上，我所拥有的是一名背景工作者。单击一个按钮，该按钮具有BackgroundWorker.DoWork DoWork功能具有以下代码：

For Each item In lst_Folders.CheckedItems
        Dim path As String = My.Settings.stng_sourceDirectory + "\" + item.Text
        For Each dirPath As String In Directory.GetDirectories(path, "*", SearchOption.AllDirectories)
            Directory.CreateDirectory(dirPath.Replace(path, My.Settings.stng_saveDirectory + "\" + item.Text))
        Next

        'Copy all the files & Replaces any files with the same name
        For Each newPath As String In Directory.GetFiles(path, "*.*", SearchOption.AllDirectories)
            File.Copy(newPath, newPath.Replace(path, My.Settings.stng_saveDirectory + "\" + item.Text), True)
        Next
 Next

它基本上是复制和粘贴目录，具体取决于检查哪个ListViewItem。问题是，一旦我点击按钮，背景确实有效，但我立即收到错误

Cross-thread operation not valid: Control 'lst_Folders' accessed from a thread other than the thread it was created on.

有人可以帮我解决这个问题。我不知道为什么它不起作用。

Answer 1

您应该只访问UI线程上的UI控件属性。运行后台工作程序时，可以将参数传递给它。我建议您从UI复制所需的值，并将它们作为参数传递给后台工作程序，而不是让后台工作程序直接读取UI。

例如，在事件处理程序中执行以下操作：

Private Sub startAsyncButton_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles startAsyncButton.Click

    Dim folderNames As New List(Of String)
    For Each item In lst_Folders.CheckedItems
        folderNames.Add(item.Text)
    Next
    backgroundWork.RunWorkerAsync(folderNames)

在你的工作方法中：

' This event handler is where the time-consuming work is done. 
Private Sub backgroundWorker1_DoWork(ByVal sender As System.Object, _
ByVal e As DoWorkEventArgs) Handles backgroundWorker1.DoWork
    Dim worker As BackgroundWorker = CType(sender, BackgroundWorker)
    Dim folderNames As List(of String) = CType(e.Argument, List(Of String))

    For Each folderName In folderNames
        Dim path As String = My.Settings.stng_sourceDirectory + "\" + folderName
    ' ...

有关详细信息，请参阅：BackgroundWorker.RunWorkerAsync Method (Object)

For Loop Inside BackgroundWorker.DoWork

1 个答案: